Friday, May 30, 2014

PCB Solder Mask Design Basics - Standards, Materials and Processes

PCB Solder Mask Design Basics - Standards, Materials and Processes:

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Plated Through-Holes and Filled Vias - UltraSource

Plated Through-Holes and Filled Vias - UltraSource:

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Thursday, May 22, 2014

Rounded PADs for Lead Free (RoHS)

Solder &  PCB Issues for Lead Free (RoHS)


"Increase spacing between pads to minimise risk from bridging
Align multi-pin components parallel to solder transport direction
As wetting is inferior, use smaller pads to ensure that no pad areas remain without solder. This will be important for equipment used in corrosive environments. “Rounding” of corners of pads helps prevent thermal decomposition of flux at higher lead-free temperatures."



















More about rounded pads - IPC-7351B

PCB Libraries Forum



















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Friday, May 16, 2014

DFM - Laminate Slivers


















"In PCB fabrication process, a copper sliver can cause material to detach during photo-imaging processes in fabrication. Floating pieces can cause defects and shorts which reduce yield. In electric performance aspect, slivers can even contribute to inconsistent impedance if they exit in plane layer."


Source: High Volume Overseas Contract Manufacturer

Sunday, May 11, 2014

Copper Thieving

Copper Thieving: "If you noticed it, the other common misconception that Lee clears up here is on “copper balancing” to avoid warped boards. There is no need to balance copper on a PCB today. Period."

Source: http://www.freelists.org/post/si-list/Impact-on-Copper-Thieving-on-10G-Routing,3


Call Plates -  "The B-Stage material and the copper foil are sheeted and laid up in large lamination racks between large stainless steel call plates. Then the material is laminated similar to a PCB lamination process."

Source: http://www.laocsmta.org/archive/Park_Nelco_Meeting_Review.pdf


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Bypass cap location is irelevant

Bypass cap location is irelevant:

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